Device for obtaining impression



C088 ENCE SEARCH RSS5?! Aug. 21, 1962 R. N]. JORDA EI'AL 3,049,752

DEVICE FOR OBTAINING IMPRESSION Filed Dec. 25. 1959 INVENTORSI R. M.JORDA R.P. YACHIK THEIR ATTORNEY 3,049,752 DEVICE FOR OBTAININGIMPRESSION Robert M. Jorda, Houston, Tex., and Royal P. Yachik, GardenGrove, Califi, assignors to Shell Gil Company, a corporation of DelawareFiled Dec. 23, 1959, Ser. No. 861,471 3 Claims. (Cl. 18-5) Thisinvention relates to oil well equipment and more particularly to adevice for obtaining an impression of an oil well casing or othertubular members.

One of the major problems in oil wells is the obtaining of informationwhich indicates the extent of internal corrosion of the well casing orthe conditions of the perforations in the liner. In the past, it hasbeen suggested that deformable members be lowered into the well and thenexpanded by means of internal pressure to obtain an impression of theinner surface of the casing. The deformable member was then collapsedand the device withdrawn from the well leaving an impression of thecorrosion or the perforations on the outer surface of the deformablemember. While such a device is satisfac tory it has severaldisadvantages, for example, if the deformable member is not completelycollapsed the impression obtained on its outer surface Will be partiallydestroyed during withdrawal of the device. Furthermore, in using such adevice it is necessary to supply a source of pressurized fluid to thedevice in order to expand the deformable member into contact with theinner surface of the casing. This requires the running of a conduit orpipe string into the well in order to supply the fluid pressure to thedevice as it is lowered into position. Thus, the devices of the priorart are expensive to run and at times fail to give satisfactory results.

Accordingly, it is the principal object of this invention to provide anovel device for obtaining an impression of the inner surface of an oilwell casing which may be lowered and retrieved from a well by means of awire line.

It is a further object of this invention to provide a. unique device forobtaining an impression of the inner surface of the well which utilizesa mechanical movement for expanding the deformable members into contactwith the inner surface of the casing and then mechanically retracts thedeformable members in order that the device may be withdrawn from thewell without injuring or destroying the impression on the outer surfaceof the deformable member.

The above objects and advantages of this invention are obtained by adevice utilizing a plurality of deformable members arranged as theindividual segments of a cylindrical member. Each of the members isfastened to a mechanical expanding means which is driven by a reversibleelectrical motor. The electrical motor will thus move the individualsegments outwardly into contact with the inner surface of the casing toobtain an impression of the casing surface and then retract theminwardly so that the device may be removed from the well. The mechanicalmovement is arranged so that when the segments are moved outwardly theouter surface of the segments remain substantially parallel with theaxis of the casing and thus a clear and distinct impression of thesurface is obtained. The device is lowered into the well on the end of acable which in addition contains suitable electrical conductors forsupplying power to the reversible motor. The use of a single cablepermits the device to be lowered and retrieved from the well in a mannersimilar to that used for lowering other wire line equipment. The use ofwire line equipment in oil wells is well known in the art and will notbe described in this application.

The above and other objects of this invention will be i ii more easilyunderstood from the following detailed description of a preferredembodiment when taken in conjunction with the attached drawing showingan elevation view partly in section of one device constructed inaccordance with this invention.

Referring now to the drawing there is shown a device constructedaccording to this invention disposed in a section of an oil well casing10. While the device is shown and described as being used for obtainingimpressions of an oil well casing or liner it is of course to beunderstood that the device may be used for obtaining the impressions ofthe inner surface of any similar tubular member. The device is loweredinto the casing and retrieved on the end of a cable 11 which containssuitable electrical conductors 16 for supplying power to the reversibleelectric motor 20. The lower end of the cable is secured to apressure-tight housing 12 by means of a suspension flange 13 with asealing means 14 being disposed around the cable to insure apressuretight seal around the cable 11. The housing 12 is formed from acup-shaped member 17 and a bottom plate 18 which is secured to thecup-shaped member 17 by a plurality of bolts 19. A sealing ring 21 isdisposed between the mating flanges of the cup-shaped member 17 andbottom plate 18 to insure a tight seal. Four centralizing members 15 aresecured to the outer surface of the cup shaped member 17 for aligningthe axis of the housing with the axis of the casing. The centralizingmembers 15 are preferably formed of a spring type material in order thatthey may have sufficient resiliency to allow easy passage of the devicepast irregularities or obstructions in the casing. The motor 20 isdisposed within the housing 12 and supported by means of motor supports27 which extend downwardly from the motor casing and are fastened to thebottom plate 18 by any desired means such as welding or the like. Themotor shaft 22 extends from the lower end of the motor through thebottom plate 18 of the pressure-tight housing 12. The shaft opening inthe bottom plate is sealed by means of a sealing ring 23 or othersealing arrangement.

Secured to the lower end of the motor shaft 22 is a drive shaft 29having two threaded portions 24 and 28. The threaded portions 24 and 28on the drive shaft should have threads having opposite direction ofadvancement in order that two nut members 25 and 30 will be drawntogether or moved apart depending upon the direction of rotation of themotor 20. A spline or guide member 31 is fastened to the bottom plate 18of the pressuretight housing 12 and extends downwardly to engage a slotformed in the nut members 25 and 30. The spline 31 thus preventsrotation of the nut members and insures that they will travellongitudinally along the threaded portions 24 and 28 as the motorrotates.

A plurality of impression pad holders 32 are secured to the two nutmembers 25 and 30 by toggle links 33. The opposite ends of the togglelinks 33 are pivotally connected to both the impression pad holders 32and the nut members 25 and 30, respectively. While any number ofimpression pad holders may be used it is preferable to use at least twoin order to obtain an impression of substantially the complete innersurface of the casing. The area covered by the device will be increasedas more holders are utilized since the space between the individualsegments can be made smaller and still insure that the segments may bemoved radially out to obtain an impression and then retracted to permitwithdrawal of the device from the well. Removably secured to the outersurface of the impression pad holders 32 are impression pads 34. Theimpression pads 34 are formed of a material which maybe easily deformedby the irregularities on the inner surface of the casing as theimpression pad is moved radially outwardly and remain in this deformedstate after they are withdrawn from contact with the inner surface ofthe casing. Suitable materials are soft metallic materials, for example,lead or the like or plastic materials, for example, raw rubber. If rawrubber is used it will be necessary to supply sufiicient heat to cure orvulcanize the rubber after the impression pads have been moved intocontact with the inner surface of the casing. In some cases, the heatrequired for vulcanizing the raw rubber may be the heat of the formationsurrounding the casing while in cases where the formation heat is notsufficient electrical heating ele ments may be incorporated in theimpression pads. After the raw rubber has been vulcanized the impressionformed on the surface of the impression pads will remain.

In operating the above-described tool the complete assembly is loweredinto the well casing or liner to a predetermined depth, the depth beinglocated at the point in the casing at which it is desired to obtain anindication of the condition of the inner surface of the casing.Electrical power is then transmitted to the reversible motor in order torotate the lead screw in a direction to draw the nut members and closertogether. The action of the screw driven toggle members will then movethe impression pad holders 32 radially outwardly while maintaining theouter surface of the impression pads 34 substantially parallel with theaxis of the casing. In order to insure this parallel movement theindividual toggle links 33 should all be of substantially the samelength and the nut members 25 and 30 should be properly positioned alongthe threaded portion of the drive shaft 29. This radial movement willthen press the deformable impression pads against the inner surface ofthe casing and the mechanical advantage of the toggle mechanism willapply sufiicient pressure to the impression pads 34 to obtain a welldefined impression of the surface even though relatively stiff metalsuch as lead or the like is used for the impression pads. After theimpression has been obtained the direction of rotation of the motor 20is reversed in order to retract the impression pads from the surface ofthe casing. After the impression pads have been retracted the device maybe withdrawn from the well and the impression pads inspected toascertain the condition of the surface of the casing.

From the above description it should be noted that it is possible tocompletely retract the impression pads in order that the device may bewithdrawn from the well without injuring or damaging the impressioncontained on the pads. Furthermore, the only equipment required foroperating the device is a suitable cable 11 and a source of electricpower at the surface of the well. This greatly simplifies the use of thedevice since it is not necessary to supply pressurized fluid to thedevice as it is lowered into the well in order to expand the impressionmember into contact with the surface of the casing. Also, the use ofindividual impression pads 34 which are mechanically moved into contactwith the inner surface of the well eliminates the necessity ofpressure-tight fittings for attaching the deformable members to thedevice on which they are mounted for containing the expanding pressure.Thus, this invention provides a novel impression device which may belowered into a well by means of a wire line or cable to obtain anaccurate impression of the inner surface of the casing. Accordingly,this invention should not be limited to the particular details describedbut only to its broad spirit and scope.

We claim as our invention:

1. A device for obtaining an impression of the inner surface of atubular member comprising: an expanding impression element formed from aplurality of individual segmented impression pad holders; a deformableimpression pad mounted on the outer surface of each pad holder; at leasttwo substantially equal toggle links pivotally secured to each padholder at one end and pivotally secured to threaded nuts at theiropposite ends; a threaded lead screw passing through both nuts, saidtoggle links and nuts being disposed with the surface of the impressionpad substantially parallel with the axis of the lead screw; a reversibleelectric motor disposed in a housing and coupled to said lead screw;centering elements disposed on said housing for substantially aligningthe axis of said lead screw and motor with the axis of the tubularmember; and means for suspending said housing on a cable to lower saidhousing into the tubular member and retrieve said housing.

2. A device for obtaining an impression of the inner surface of atubular member comprising: a tubular expanding impression element formedfrom a plurality of individual elongated segmented impression padholders; a deformable impression pad mounted on the outer surface ofeach pad holder; at least two substantially equal length toggle linksbeing pivotally secured to each pad holder, the opposite end of eachlink being pivotally secured to one of two nut members, both of said nutmembers being disposed on a lead screw; a pressure-tight housing adaptedto be secured to the end of a cable for lowering and retrieving from theinterior of a tubular member; an electric motor disposed within saidhousing and having a motor shaft projecting through said housing, saidmotor shaft being coupled to said lead screw; guide means projectingfrom said housing and engaging said nut members to prevent rotation ofsaid nut member when the lead screw rotates; and resilient centermembers secured to said housing to align the axis of said housing withthe axis of the tubular member.

3. A device for obtaining an impression of the inner surface of anopening formed in a material comprising: an expanding impression elementformed from a plurality of individual segmented impression pad holders;a deformable impression pad mounted on the outer surface of each padholder; at least two substantially equal toggle links pivotally securedto each pad holder at one end and pivotally secured to threaded nuts attheir opposite ends; a threaded lead screw passing through both nuts,said toggle links and nuts being disposed with the surface of theimpression pad substantially parallel with the axis of the lead screw;means for driving said lead screw to expand said impression pad holdersinto contact with the inner surface of the opening to obtain animpression thereof and then retract said impression pad holders, wherebysaid pads are held from contacting the surface when in the retractedposition; means coupled to the device for lowering the device into theopening and retrieving the device after said impression pad holders areretracted and centering means on said device to maintain the device inalignment with the axis of the opening.

References Cited in the file of this patent UNITED STATES PATENTS214,500 Felthousen Apr. 22, 1879 869,520 Robbins Oct. 29, 1907 1,026,525McKeel et a1. May 14, 1912 1,497,190 Moland June 10, 1924 2,102,080Kinley Dec. 14, 1937 2,405,245 Ushakoif Aug. 6, 1946 2,416,441 Grant etal. Feb. 25, 1947 2,618,014 Sawyer et al Nov. 18, 1952 2,653,474Santiago Sept. 29, 1953 2,972,156 Ver Nooy Feb. 21, 1961

